HIV Research Today is a free monthly online journal that collates and summarizes the latest research about HIV, including details on human immunodeficiency virus, testing, treatment, prevention, vaccines, aids.

Molecular clock-like evolution of human immunodeficiency virus type 1.

Liu Y, Nickle DC, Shriner D, Jensen MA, Learn GH, Mittler JE, Mullins JI

Department of Microbiology, University of Washington School of Medicine, Seattle, WA 98195, United States. yiliu197@u.washington.edu

The molecular clock hypothesis states that the rate of nucleotide substitution per generation is constant across lineages. If generation times were equal across lineages, samples obtained at the same calendar time would have experienced the same number of generations since their common ancestor. However, if sequences are not derived from contemporaneous samples, differences in the number of generations may be misinterpreted as variation in substitution rates and hence may lead to false rejection of the molecular clock hypothesis. A recent study has called into doubt the validity of clock-like evolution for HIV-1, using molecular sequences derived from noncontemporaneous samples. However, after separating their within-individual data according to sampling time, we found that what appeared to be nonclock-like behavior could be attributed, in most cases, to noncontemporaneous sampling, with contributions also likely to derive from recombination. Natural selection alone did not appear to obscure the clock-like evolution of HIV-1.

Published 12 October 2004 in Virology, 329(1): 101-8.
Full-text of this article is available online (may require subscription).

© 2004-2008 HIV Research Today. All Rights Reserved.